The present invention relates generally to magnetic resonance imager (MRI) systems and components. More particularly, the present invention relates to radio frequency shielding of an MRI magnet structure from MRI system supporting electronics for proximate and integrated coupling therebetween.
Current Magnetic Resonance Imager (MRI) systems include a superconducting magnet structure that generates a temporally constant primary magnetic field. The superconducting magnet is used in conjunction with a magnetic gradient coil assembly, which is sequentially pulsed to create a sequence of controlled gradients in the static magnetic field during a MRI data gathering sequence. The controlled sequential gradients are effectuated throughout a patient imaging volume (patient bore), which is coupled to one or more MRI radio frequency (RF) coils or antennae. The RF coils are located between the magnetic gradient coil assembly and the patient bore.
As a part of a typical MRI, RF signals of suitable frequencies are transmitted into the patient bore. Nuclear magnetic resonance (nMR) responsive RF signals are received from the patient via the RF coils. Information encoded within the frequency and phase parameters of the received RF signals, by the use of a RF circuit, is processed to form visual images. These visual images represent various desired properties of the distribution of nMR nuclei within a cross-section or volume of a patient being scanned within the patient bore.
Various system electronics are utilized to support operation of and process data collected from the MRI system. A majority of the electronics is located separate from and in a different room than the MRI magnet structure. The electronics are located in a separate room to prevent the generation of RF broadband noise, which introduces artifacts in the visual images.
When a break or varying contact between electrical connections occurs in the magnetic field of the magnet RF noise is induced in the magnetic field that causes image artifacts. Image artifacts can even be caused by the motion or rubbing of braided wire, which also induces RF noise. Thus, any metal-to-metal contact on or near the magnet structure can have varying contact and be a source of image artifacts. The artifacts are seen as “white pixels” in the acquired images.
By having the electronics in a separate room from the magnet structure, additional floor space is required. Floor space within an examining facility, such as a hospital, is costly and has limited availability. Also, in order to have the electronics separate from the magnet structure, additional tasks are performed by the MRI system manufacturer, which increases costs of the MRI system.
Thus, there exists a need for an improved MRI system that allows the existence of both the MRI magnet structure and supporting electronics to coexist within a single room without the generation of image artifacts, caused by the close proximity of the supporting electronics with the magnet structure.